For the third and last time. If Congress is not regulating that interstate activity, then what difference does it make if your activity affects it? Who cares?
The ONLY time Congress is interested in what commerce you're doing is if it screws up what they're attempting to regulate.
Since they're regulating the airwaves, your little startup radio station is going to mess with other stations and screw things up.
You want to sell homemade radios, go for it.
If I want to do anything in any area that Congress isn't currently regulating or restricting, I can do so, even if it involves an area where Congress has explicit authority.
But the question isn't what Congress isn't currently regulating. The question is what commerce-related activities exist which Congress could not at any time decide to regulate by declaring that they might affect interstate commerce.
If no such activities exist, then the limitation of Congress' power to commerce "among the several states, etc." is analagous to saying "Congress may only restrict the ownership of firearms which are comprised of atoms." In owner words, the words "among the several states, etc." mean nothing.
Of course, if such activities do exist (that Congress could not take control over by declaring that they might affect interstate commerce), perhaps you might be able to name one?